The present invention concerns functionalized alkenes, along with alkane and alkyne analogs thereof, that have pesticidal activity, along with methods of use thereof.
Many blood-ingesting pests are known to feed on humans and animals, and many pests are vectors for pathogenic microorganisms which threaten human and animal health, including commercially important livestock, pets and other animals. Various species of mosquitoes, for example, transmit diseases caused by viruses, and many are vectors for disease-causing nematodes and protozoa. Mosquitoes of the genus Anopheles transmit Plasmodium, the protozoan which causes malaria, a devastating disease which results in approximately 1 million deaths annually. The mosquito species Aedes aegypti transmits an arbovirus that causes yellow fever in humans. Other arboviruses transmitted by Aedes species include the causative agents, of dengue fever, eastern and western encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis, chikungunya, oroponehe and bunyarnidera. The genus Culex, which includes the common house mosquito C. pipiens, is implicated in the transmission of various forms of encephalitis and filarial worms. The common house mosquito also transmits Wuchereria banuffi and Brugia malayi, which cause various forms of lymphatic filariasis, including elephantiasis. Trypanasomas cruzi, the causative agent of Chagas"" disease, is transmitted by various species of blood-ingesting Triatominae bugs. The tsetse fly (Glossina spp.) transmits African trypanosomal diseases of humans and cattle. Many other diseases are transmitted by various blood-ingesting pest species. The order Diptera contains a large number of blood-ingesting and disease-bearing insects, including, for example, mosquitoes, black flies, no-see-ums (punkies), horse flies, deer flies and tsetse flies.
Various pesticides have been employed in efforts to control or eradicate populations of disease-bearing pests, such as disease-bearing blood-ingesting pests. For example, DDT, a chlorinated hydrocarbon, has been used in attempts to eradicate malaria-bearing mosquitoes throughout the world. Other examples of chlorinated hydrocarbons are BHC, lindane, chlorobenzilate, methoxychlor, and the cyclodienes (e.g., aldrin, dieldrin, chlordane, heptachlor, and endrin). The long-term stability of many of these pesticides and their tendency to bioaccumulate render them particularly dangerous to many non-pest organisms.
Another common class of pesticides is the organophosphates, which is perhaps the largest and most versatile class of pesticides. Organophosphates include, for example, parathion, Malathion, diazinon, naled, methyl parathion, and dichlorvos. Organophosphates are generally much more toxic than the chlorinated hydrocarbons. Their pesticidal effect results from their ability to inhibit the enzyme cholinesterase, an essential enzyme in the functioning of the insect nervous system. However, they also have toxic effects on many animals, including humans.
The carbamates, a relatively new group of pesticides, include such compounds as carbamyl, methomyl, and carboftiran. These compounds are rapidly detoxified and eliminated from animal tissues. Their toxicity is thought to involve a mechanism similar to the mechanism of the organophosphates; consequently, they exhibit similar shortcomings, including animal toxicity.
A major problem in pest control results from the capability of many species to develop pesticide resistance. Resistance results from the selection of naturally-occurring mutants possessing biochemical, physiological or behavioristic factors that enable the pests to tolerate the pesticide. Species of Anopheles mosquitoes, for example, have been known to develop resistance to DDT and dieldrin. DDT substitutes, such as Malathion(trademark), propoxur and fenitrothion are available; however, the cost of these substitutes is much greater than the cost of DDT.
There is clearly a longstanding need in the art for pesticidal compounds that are pest-specific, that reduce or eliminate direct and/or indirect threats to human health posed by presently available pesticides, that are environmnentally compatible in the sense that they are biodegradable, are not toxic to non-pest organisms, and have reduced or no tendency to bioaccummulate.
Many pests, including for example blood-imbibing pests, must consume and digest a proteinaceous meal to acquire sufficient essential amino acids for growth, development and the production of mature eggs. Adult pests, such as adult mosquitoes, need these essential amino acids for the production of vitellogenins by the fat body. These vitellogenins are precursors to yolk proteins which are critical components of oogenesis. Many pests, such as house flies and mosquitoes, produce oostatic hormones that inhibit egg development by inhibiting digestion of the protein meal and thereby limiting the availability of the essential amino acids necessary for egg development.
Serine esterases such as trypsin and trypsin-like enzymes (collectively referred to herein as xe2x80x9cTTLExe2x80x9d) are important components of the digestion of proteins by insects. In the mosquito, Aedes aegypti, an early trypsin that is found in the midgut of newly emerged females is replaced, following the blood meal, by a late trypsin. A female mosquito typically weighs about 2 mg and produces 4 to 6 ug of trypsin within several hours after ingesting a blood meal. Continuous boisynthesis at this rate would exhaust the available metabolic energy of a female mosquito; as a result, the mosquito would be unable to produce mature eggs, or even to find an oviposition site. To conserve metabolic energy, the mosquito regulates TTLE biosynthesis with a peptide hormone named Trypsin Modulating Oostatic Factor (TMOF). Mosquitoes produce TMOF in the follicular epithelium of the ovary 12-35 hours after a blood meal; TMOF is then released into the hemolymph where it binds to a specific receptor on the midgut epithelial cells, signaling the termination of TTLE biosynthesis. This regulatory mechanism is not unique for mosquitoes; flesh flies, fleas, sand flies, house flies, dog flies and other insect pests which need protein as part of their diet have similar regulatory mechanisms.
In 1985, Borovsky purified an oostatic hormone 7,000-fold and disclosed that injection of a hormone preparation into the body cavity of blood imbibed mosquitoes caused inhibition of egg development and sterility (Borovsky, D. [1985] Arch. Insect Biochem. Physiol. 2:333-349). Following these observations, Borovsky (Borovsky, D. [1988] Arch. Ins. Biochem. Physiol. 7:187-210) reported that injection or passage of a peptide hormone preparation into mosquitoes inhibited the TTLE biosynthesis in the epithelial cells of the gut. This inhibition caused inefficient digestion of the blood meal and a reduction in the availability of essential amino acids translocated by the hemolymph, resulting in arrested egg development in the treated insect. Borovsky observed that this inhibition of egg development does not occur when the oostatic hormone peptides are inside the lumen of the gut or other part of the digestive system (Borovsky, D. [1988], supra).
Following the 1985 report, the isolated hormone, (a ten amino acid peptide) and two TMOF analogues were disclosed in U.S. Pat. Nos. 5,011,909 and 5,130,253, and in a 1990 publication (Borovsky et al. [1990] FASEB J. 4:3015-3020). Additionally, U.S. Pat. No. 5,358,934 discloses truncated forms of the full length TMOF which have prolines removed from the carboxy terminus, including the peptides YDPAP, YDPAPP, YDPAPPP, and YDPAPPPP.
D. Borovsky and R. Linderman, U.S. patent application Ser. No. 09/295,996, filed Apr. 21, 1999, now U.S. Pat. No. 6,413,530 discloses additional novel peptides and the use thereof to control insect pests.
TMOF analogs that have been identified to date are primarily peptide analogs. In order to provide a greater diversity of new pesticidal compounds, it would be desirable to possess compounds that are TMOF analogues, yet are not peptides.
The present invention is based on the discovery of non peptide organic compounds that have a structure analogous to or reminiscent of the TMOF structure and have pesticidal activity. Thus the present invention concerns pesticidal compounds that inhibit digestion in pests by terminating or otherwise blocking synthesis of digestive enzymes by activating a TMOF receptor (collectively referred to herein as xe2x80x9cpesticidal compoundsxe2x80x9d). The pesticidal compounds and other compounds of the present invention are usefully employed in the control of pests, particularly insect pests such as mosquitoes, which ingest blood.
Thus, a first aspect of the present invention is a method of controlling a pest such as an insect pest, comprising administering to said pest a pesticidally effective amount of a non-peptide TMOF analog (that is, an organic compound that has TMOF activity). This definition is specifically intended to exclude the peptide TMOF agonists or analogs disclosed in, inter alia, U.S. Pat. Nos. 5,011,909; 5,130,253; and 5,358,934, the disclosures of which are incorporated by reference herein in their entirety.
Particular pesticidal compounds/non-peptide TMOF analogs of the present invention have the formula I below: 
wherein:
X is selected from the group consisting of xe2x80x94CHCHxe2x80x94, xe2x80x94CH2CH2xe2x80x94, and xe2x80x94CCxe2x80x94;
Z is selected from the group consisting of xe2x80x94OH, xe2x80x94NH2 and xe2x80x94OR6 wherein R6 is loweralkyl;
n and m are each at least 1 and together total an integer from 2, 3 or 4 to 6, 8, 10 or 12; and
R1, R2, R3, R4, and R5 are each independently selected from the group consisting of xe2x80x94H, xe2x80x94OH, halo, loweralkyl, and loweralkoxy; subject to the proviso that:
a pair of R1 and R2, R2 and R3, or R3 and R4 on the phenyl ring may together represent xe2x80x94CR7xe2x95x90CR8xe2x80x94CR9xe2x95x90CR10xe2x80x94, to form with the phenyl ring illustrated above a naphthyl ring system, wherein R7, R8, R9, and R10 are each independently selected from the group consisting of xe2x80x94H, xe2x80x94OH, halo, loweralkyl, and loweralkoxy.
A second aspect of the present invention is a method of initiating a TMOF receptor-mediated biological response. The method comprises contacting to a TMOF receptor in vivo or in vitro for a time and in an amount sufficient to initiate a TMOF receptor-mediated biological response a compound of Formula I as described herein. The biological response may be any suitable biological response mediated by the TMOF receptor, including but not limited to inhibition of biosynthesis of a digestive enzyme such as trypsin.
As noted above, the pesticidal compounds of the present invention have advantageous biological activity against pests. The novel compounds of the invention are particularly active against blood-sucking insects, particularly against species of mosquitoes such as Aedes aegypti that are common vectors of arthropod-borne viral diseases, such as arboviruses. Other biting pests such as flies, fleas, ticks, and lice can also be controlled using compounds and methods of the subject invention. These pests utilize TTLE as their primary blood-digesting enzymes.
The subject compounds can also be used to control pests of agricultural crops, for example by applying the compounds to the agricultural crops. These pests include, for example, coleopterans (beetles), lepidopterans (caterpillars), and mites. The compounds of the subject invention can also be used to control household pests including, but not limited to, ants and cockroaches.
Another aspect of the subject invention pertains to a method for controlling pests, particularly insect pests, comprising administering to said pest a pesticidally effective amount of a pesticidal compound of the subject invention.
The subject invention provides pest control compositions comprising pesticidal compounds and a suitable pesticidal carrier. The pest control compositions are formulated for application to the target pests or their situs.
The methods and materials of the subject invention provide a novel approach to controlling insects and insect-transmitted diseases. The compounds of the subject invention have advantageous activity and increased resistance to proteolysis over previously disclosed compounds.
As used herein, the term xe2x80x9cpesticidally effectivexe2x80x9d is used to indicate an amount or concentration of a pesticidal compound which is sufficient to reduce the number of pests in a geographical locus as compared to a corresponding geographical locus in the absence of the amount or concentration of the pesticidal compound.
The term xe2x80x9cpesticidalxe2x80x9d is not intended to refer only to the ability to kill pests, such as insect pests, but also includes the ability to interfere with a pest""s life cycle in any way that results in an overall reduction in the pest population. For example, the term xe2x80x9cpesticidalxe2x80x9d includes inhibition of a pest from progressing from one form to a more mature form, e.g., transition between various larval instars or transition from larva to pupa or pupa to adult. Further, the term xe2x80x9cpesticidalxe2x80x9d is intended to encompass anti-pest activity during all phases of a pest""s life cycle; thus, for example, the term includes larvacidal, ovicidal, and adulticidal activity.
The term xe2x80x9cloweralkylxe2x80x9d as used herein means C1 to C4 alkyl, preferably methyl, ethyl or propyl.
The term xe2x80x9cloweralkoxyxe2x80x9d as used herein means C1 to C4 alkoxy, preferably methoxy, ethoxy, or propoxy.
The term xe2x80x9chaloxe2x80x9d as used herein means halogen, preferably fluoro, chloro, bromo or iodo, most preferably fluoro.
1. Pesticidal Compounds
Compounds useful in the present invention have the general formula I below: 
wherein:
X is selected from the group consisting of xe2x80x94CHCHxe2x80x94, xe2x80x94CH2CH2xe2x80x94, and xe2x80x94CCxe2x80x94;
Z is selected from the group consisting of xe2x80x94OH, xe2x80x94NH2 and xe2x80x94OR6 wherein R6 is loweralkyl;
n and m are each at least 1 and together total an integer from 2, 3 or 4 to 6, 8, 10 or 12; and
R1, R2, R3, R4, and R5 are each independently selected from the group consisting of xe2x80x94H, xe2x80x94OH, halo, loweralkyl, and loweralkoxy; subject to the proviso that:
a pair of R1 and R1, R2 and R3, R3 and R4, or R4 and R5 on the phenyl ring may together represent xe2x80x94CR7xe2x95x90CR8xe2x80x94CR9xe2x95x90CR10xe2x80x94, to form with the phenyl ring illustrated above a naphthyl ring system, wherein R7, R8, R9, and CR10 are each independently selected from the group consisting of xe2x80x94H, xe2x80x94OH, halo, loweralkyl, and loweralkoxy.
Preferred compounds of formula I above have the general formula II as given below: 
wherein Z, n, m, R1, R2, R3, R4, and R5 are as described above. In compounds of formula II, the phenyl ring and the carbonyl carbon may be either cis (Z) or trans (E) with respect to one another. The trans configuration is preferred.
Specific examples of compounds as described above include:
E-7-phenylhept-4-enoic acid, which has the structure: 
E-7-(4-methoxyphenyl)hept-4-enoic acid, which has the structure: 
Methyl E-7-phenylhept-4-enoate, which has the structure: 
E-7-phenylhept-4-enoic acid amide, which has the structure: 
Z-7-phenylhept-4-enoic acid, which has the structure: 
E-7-(2,4-difluorophenyl)hept-4-enoic acid, which has the structure: 
E-10-phenyldec-6-enoic acid, which has the structure: 
and E-10-(4-methoxyphenyl)dec-4-enoic acid, which has the structure: 
Additional examples of acids of the present invention include:
E-7-(4-hydroxyphenyl)hept-4-enoic acid;
E-7-(2,4-dibromophenyl)hept-4-enoic acid;
E-7-(4-methylphenyl)hept-4-enoic acid;
E-7-(2,4-diethylphenyl)hept-4-enoic acid;
E-7-(2-ethoxyphenyl)hept-4-enoic acid;
E-7-(2,4,-dipropoxyphenyl)hept-4-enoic acid; and
E-10-(2,4-difluorophenyl)dec-4-enoic acid.
Additional examples of amides of the present invention include:
E-7-(2,4-difluorophenyl)hept-4-enoic acid amide;
E-7-(4-methoxyphenyl)hept-4-enoic acid amide;
E-10-phenyldec-6-enoic acid amide;
E-7-(2,4-difluorophenyl)dec-6-enoic acid amide;
E-7-(4-methoxyphenyl)dec-6-enoic acid amide; and
Z-7-phenylhept-4-enoic acid amide.
Additional examples of esters of the present invention include:
Methyl E-7-(2,4-difluorophenyl)hept-4-enoate;
Methyl E-7-(4-methoxyphenyl)hept-4-enoate;
Methyl E-10-phenyldec-6-enoate;
Methyl E-7-(2,4-difluorophenyl)dec-6-enoate;
Methyl E-7-(4-methoxyphenyl)dec-6-enoate;
Methyl Z-7-phenylhept-4-enoate;
Ethyl E-7-(2,4-difluorophenyl)hept-4-enoate;
Ethyl E-7-(4-methoxyphenyl)hept-4-enoate;
Ethyl E-10-phenyldec-6-enoate;
Propyl E-7-(2,4-difluorophenyl)dec-6-enoate;
Propyl E-7-(4-methoxyphenyl)dec-6-enoate;
Propyl Z-7-phenylhept-4-enoate;
Ethyl E-7-phenylhept-4-enoate;
Propyl E-7-phenylhept-4-enoate;
Butyl E-7-phenylhept 4-enoate;
Ethyl E-10-phenyldec-6-enoate;
Propyl E-10-phenyldec-6-enoate; and
Butyl E10-phenyldec-6-enoate.
In all of the specific alkene active compounds named above, the double bond can be replaced with a single bond to produce an analogous series of active compounds that are alkanes.
In all of the specific alkene active compounds named above, the double bond can be replaced with a triple bond to produce an analogous series of active compounds that are alkynes.
In all of the specific alkene, alkane and alkyne compounds illustrated above, the phenyl ring can be replaced with a naphthyl ring to produce an analogous series of active compounds based upon a naphthyl ring system.
Compounds of the present invention can be made by the techniques described in the Examples below, or variations thereof that will be apparent to those skilled in the art.
Compounds of the present invention can be made by the technique described in M. Ansell and J. Ducker, Reduced cyclic Compounds. Part XI. The Cyclisation of xcfx89-Arylalkenoic Acids, J. Chem. Soc. 206-212 (1961), or variations thereof that will be apparent to those skilled in the art.
A further aspect of the subject invention are addition salts, complexes, or prodrugs such as esters of the compounds described herein, especially the nontoxic pharmaceutically or agriculturally acceptable acid addition salts. The acid addition salts can be prepared using standard procedures in a suitable solvent from the parent compound and an excess of an acid, such as hydrochloric, hydrobromic, sulfuric, phosphoric, acetic, maleic, succinic, ethanedisulfonic or methanesulfonic acids. Esterification to form derivatives such as the methyl or ethyl esters, can also be performed using standard procedures. Tartarate salts can be prepared in accordance with standard procedures.
Also, derivation of the pesticidal compounds with long chain hydrocarbons will facilitate passage through the cuticle into the pest body cavity. Therefore, in a further embodiment, the subject invention provides compositions comprising the pesticidal compounds bound to lipids or other carriers.
2. Methods and Formulations for Control of Pests
The subject invention concerns novel pest control compounds and methods for using such compounds. Specifically exemplified are novel pesticidal compounds, compositions comprising said pesticidal compounds and the use of such pesticidal compounds and compositions in controlling pests, particularly insect pests such as mosquitoes.
Preferably, the subject compounds have an LD50 against mosquito larvae of less than 3.0 xcexcmole/ml. More preferably, the compounds have an LD50 of less than 2.0 xcexcmole/ml, and, most preferably, the compounds have an LD50 of less than 1.0 xcexcmole/ml. As used herein, xe2x80x9cLD50xe2x80x9d refers to a lethal dose of a peptide able to cause 50% mortality of larvae maintained on a diet of 1 mg/ml autoclaved yeast supplemented with the pesticidal polypeptide.
Control of pests using the pest control compounds of the subject invention can be accomplished by a variety of methods known to those skilled in the art. The plant pests that can be controlled by the compounds of the subject invention include pests belonging to the orders Coleoptera, Lepidopterans, Hemiptera and Thysanoptera. These pests all belong to the phylum Arthropod. Other pests that can be controlled according to the subject invention include members of the orders Diptera, Siphonaptera, Hymenoptera and Phthiraptera. Other pests that can be controlled by the compounds of the subject invention include those in the family Arachnida, such as ticks, mites and spiders.
The use of the compounds of the subject invention to control pests can be accomplished readily by those skilled in the art having the benefit of the instant disclosure. For example, the compounds may be encapsulated, incorporated in a granular form, solubilized in water or other appropriate solvent, powdered, and included into any appropriate formulation for direct application to the pest or to a pest inhabited locus.
Formulated bait granules containing an attractant and the pesticidal compounds of the present invention can be applied to a pest-inhabited locus, such as to the soil. Formulated product can also be applied as a seed-coating or root treatment or total plant treatment at later stages of the crop cycle. Plant and soil treatments may be employed as wettable powders, granules or dusts, by mixing with various inert materials, such as inorganic minerals (phyllosilicates, carbonates, sulfates, phosphates, and the like) or botanical materials (powdered corncobs, rice hulls, walnut shells, and the like). The formulations may include spreader-sticker adjuvants, stabilizing agents, other pesticidal additives, or surfactants.
Liquid formulations may be aqueous-based or non-aqueous (i.e., organic solvents), or combinations thereof, and may be employed as foams, gels, suspensions, emulsions, microemulsions or emulsifiable concentrates or the like. The ingredients may include theological agents, surfactants, emulsifiers, dispersants or polymers.
As would be appreciated by a person skilled in the art, the pesticidal concentration will vary widely depending upon the nature of the particular formulation, particularly whether it is a concentrate or to be used directly. The pesticidal compound will be present in the composition by at least about 0.0001% by weight and may be 99 or 100% by weight of the total composition. The pesticidal carrier may be from 0.1% to 99.9999% by weight of the total composition. The dry formulations will have from about 0.0001-95% by weight of the pesticide while the liquid formulations will generally be from about 0.0001-60% by weight of the solids in the liquid phase. These formulations will be administered at about 50 mg (liquid or dry) to 1 kg or more per hectare.
The formulations can be applied to the pest or the environment of the pest, e.g., soil and foliage, by spraying, dusting, sprinkling or the like.
The pest control compounds may also be provided in tablets, pellets, briquettes, bricks, blocks and the like which are formulated to float, maintain a specified depth or sink as desired. In one embodiment the formulations, according to the present invention, are formulated to float on the surface of an aqueous medium; in another embodiment they are formulated to maintain a depth of 0 to 2 feet in an aqueous medium; in yet another embodiment the formulations are formulated to sink in an aqueous environment.
3. Computational Chemistry Methods
Methods of identifying a non-peptide TMOF agonist from a peptide TMOF agonist are a further aspect of the present invention. Such methods typically comprise the steps of:
modeling in a computer (preferably with simulated annealing) a model peptide TMOF agonist selected from the group consisting of TMOF and peptide TMOF analogs;
determining in said computer spatial orientations for at least one key feature of said model peptide compound;
generating in said computer a putative non-peptide TMOF agonist structure, said structure including (i) said at least one key feature and (ii) spatial orientations for said at least one key feature corresponding to said spatial orientations for said at least one key feature of said model peptide compound; then
synthesizing said putative non-peptide TMOF agonist; and then
screening said putative non-peptide TMOF agonist to determine the presence of TMOF activity therein.
Peptide TMOF agonists or analogs that may be used as a basis for modeling of the instant invention include but are not limited to those disclosed in, inter alia, U.S. Pat. Nos. 5,011,909; 5,130,253; and 5,358,934, the disclosures of which are incorporated by reference herein in their entirety.
TMOF and other TMOF peptide agonists (preferably tripeptide fragments of TMOF) may be modeled by the INSIGHT(trademark) software (available through the North Carolina Super Computing Center for academic use) using a simulated annealing protocol as described by Lovas and Murphy (S. Lovas and R. Murphy, Molecular Modeling of Neuropeptides, in Neuropeptide Protocols, pp. 209-217 (Irvine, G. B.; Williams, C. H., Eds. Humana Press, NJ. 1997)) and Damewood (J. Damewood, Rev. Computational Chem. 9, 1-79 (1996). Peptide Mimetic Design with the Aid of Computational Chemistry). Composite structural data was then used to determine approximate spatial orientations for what were deemed to be key structural features, particularly as a phenyl ring and a carboxylate functional group. These data indicated a greater degree of flexibility in the N-terminus than in the C-terminus of the peptide structures. Non-peptide analogs were then subjected to energy minimization by molecular mechanics and distances between functional groups compared to the data obtained in the data set of the TMOF fragments. These data indicated a starting point for analog synthesis as exemplified by E-7-phenylhept-4-enoic acid. Actual compounds having structures corresponding to structures generated by the computational techniques are then synthesized in accordance with known techniques, and screened for activity in a bioassay such as described below. Thus, compounds produced by the method that have TMOF agonist activity and can be used in the methods described herein generally have the structure Pxe2x80x94Rxe2x80x94C, where P is a phenyl group, R is an alkane, alkene, or alkyne, and C is a carboxylate group, all of which may be substituted or unsubstituted.